treatment plants were built in the 1920s when it became clear that the capacities of the sewage farms had been exceeded, whereas the Parisian sanitation
organization waited until 1940 to start its first WWTP, Achères–Seine Aval.
The level of treatment at Berlin’s WWTPs has been constantly improved, with
tertiary treatment starting in the 1980s, while in the Paris area, it was not until
1993 that all effluents were treated. Brussels water supply was far up in the
Walloon region, and Milan was relying on medium-depth groundwaters,
which were potentially contaminated by its own industries. Neither Milan
nor Brussels had a WWTP until they were forced to do so by EU regulations
at the beginning of the 2000s.
Trajectories in these four cities, which were exposed to maximum relative
pressures (city population/river discharge), show a period of intense degradation in the late nineteenth century due to the discharge of untreated wastewater
and the related alteration to physical environments. The rapid population
growth was not followed by adequate technical, organizational or financial
means sufficient to treat domestic and industrial discharges. The Zenne River
was covered and transformed into a sewage collector across its urban sector.
The urban impact of these cities on the quality of their rivers lasted over more
than a century. The restoration of the Seine River and the Spree River was
initiated several decades before that of the Zenne and Lambro rivers. European
environmental policy played a major role in the converging restoration of all
socio-hydrosystems in the early 2000s (Fig. 5) [25].
Fig. 5 Comparative trajectories (1870–2010) of the efficiency of the social response to reduce the
organic pollution generated by four European cities in their rivers, using WFD standards and colour
coding, from blue, very efficient policy (full river restoration), to red, inefficient measures, resulting
in major degradation (summer oxygen levels occasionally below 2 mg O 2 L
À1
)
River Basin Visions: Tools and Approaches from Yesterday to Tomorrow
397
organization waited until 1940 to start its first WWTP, Achères–Seine Aval.
The level of treatment at Berlin’s WWTPs has been constantly improved, with
tertiary treatment starting in the 1980s, while in the Paris area, it was not until
1993 that all effluents were treated. Brussels water supply was far up in the
Walloon region, and Milan was relying on medium-depth groundwaters,
which were potentially contaminated by its own industries. Neither Milan
nor Brussels had a WWTP until they were forced to do so by EU regulations
at the beginning of the 2000s.
Trajectories in these four cities, which were exposed to maximum relative
pressures (city population/river discharge), show a period of intense degradation in the late nineteenth century due to the discharge of untreated wastewater
and the related alteration to physical environments. The rapid population
growth was not followed by adequate technical, organizational or financial
means sufficient to treat domestic and industrial discharges. The Zenne River
was covered and transformed into a sewage collector across its urban sector.
The urban impact of these cities on the quality of their rivers lasted over more
than a century. The restoration of the Seine River and the Spree River was
initiated several decades before that of the Zenne and Lambro rivers. European
environmental policy played a major role in the converging restoration of all
socio-hydrosystems in the early 2000s (Fig. 5) [25].
Fig. 5 Comparative trajectories (1870–2010) of the efficiency of the social response to reduce the
organic pollution generated by four European cities in their rivers, using WFD standards and colour
coding, from blue, very efficient policy (full river restoration), to red, inefficient measures, resulting
in major degradation (summer oxygen levels occasionally below 2 mg O 2 L
À1
)
River Basin Visions: Tools and Approaches from Yesterday to Tomorrow
397